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Weakness and Fatigue

Topic Overview

Weakness and fatigue are
terms that are often used as if they mean the same thing. But in fact they
describe two different sensations. It is important to know exactly what you
mean when you say "I feel weak" or "I am fatigued" because it can help you and
your doctor narrow down the possible causes of your symptoms.

Weakness is a lack of physical or muscle strength and the feeling
that extra effort is required to move your arms, legs, or other muscles. If
muscle weakness is the result of pain, the person may be able to make muscles
work, but it will hurt.

Fatigue is a feeling of tiredness or exhaustion or a need to rest
because of lack of energy or strength. Fatigue may result from overwork, poor sleep, worry, boredom, or lack of exercise. It is a symptom that may be caused by illness, medicine, or medical treatment such as chemotherapy. Anxiety or depression can also cause fatigue.

Both weakness and fatigue are symptoms, not diseases. Because
these symptoms can be caused by many other health problems, the importance of
weakness and fatigue can be determined only when other symptoms are
evaluated.

Weakness

General weakness often occurs after you have
done too much activity at one time, such as by taking an extra-long hike. You
may feel weak and tired, or your muscles may be sore. These sensations usually
go away within a few days.

In rare cases, generalized muscle
weakness may be caused by another health problem, such as:

A problem with the minerals (electrolytes) found naturally in the body, such as low
levels of potassium or sodium.

Infections, such as a urinary tract infection or a respiratory infection.

Problems with the thyroid gland, which
regulates the way the body uses energy.

Muscle weakness that is slowly getting worse requires a
visit to a doctor.

Sudden muscle weakness and loss of function in
one area of the body can indicate a serious problem within the brain (such as a
stroke or
transient ischemic attack) or
spinal cord or with a specific nerve in the body.

Fatigue

Fatigue is a feeling of tiredness,
exhaustion, or lack of energy. You may feel mildly fatigued because of
overwork, poor sleep, worry, boredom, or lack of exercise. Any illness, such as
a cold or the flu, may cause fatigue, which usually goes away as the illness
clears up. Most of the time, mild fatigue occurs with a health problem that
will improve with home treatment and does not require a visit to a
doctor.

A stressful emotional situation may also cause fatigue.
This type of fatigue usually clears up when the
stress is relieved.

Many prescription and
nonprescription
medicines can cause weakness or fatigue. The use or
abuse of alcohol, caffeine, or illegal drugs can cause fatigue.

A
visit to a doctor usually is needed when fatigue occurs along with more serious
symptoms, such as increased breathing problems,
signs of a serious illness, abnormal bleeding, or unexplained weight loss or
gain.

Fatigue that lasts longer than 2 weeks usually requires a
visit to a doctor. This type of fatigue may be caused by a more serious health
problem, such as:

A decrease in the amount of oxygen-carrying
substance (hemoglobin) found in red blood cells (anemia).

If fatigue occurs without an
obvious cause, it is important to evaluate your mental health. Fatigue is a
common symptom of mental health problems, such as
anxiety or
depression. Fatigue and depression may become so
severe that you may consider suicide as a way to end your pain. If you think
your fatigue may be caused by a mental health problem, see your doctor.

Think about whether the weakness or fatigue started after you began using a new medicine or a higher dose of a medicine.

Yes

Symptoms may be caused by a medicine

No

Symptoms may be caused by a medicine

Do you think that a mental health problem could be causing the fatigue?

Fatigue is a common symptom of problems such as depression, stress, anxiety, grief, and eating disorders.

Yes

Fatigue may be caused by mental health problem

No

Fatigue may be caused by mental health problem

In the past few weeks, have you been losing weight without trying?

Yes

Has been losing weight without trying

No

Has been losing weight without trying

Has the weakness or fatigue lasted more than 2 weeks and made it harder to do your daily activities?

Yes

Symptoms for more than 2 weeks and difficulty with daily activities

No

Symptoms for more than 2 weeks and difficulty with daily activities

Neurological symptoms—which may be
signs of a problem with the nervous system—can affect many body functions.
Symptoms may include:

Numbness, weakness, or lack of movement in your
face, arm, or leg, especially on only one side of your body.

Trouble seeing in one or both eyes.

Trouble speaking.

Confusion or trouble understanding simple statements.

Problems with balance or coordination (for example, falling down
or dropping things).

Seizures.

Seek Care Now

Based on your answers, you may need care right away. The problem is likely to get worse without medical care.

Call your doctor now to discuss the symptoms and
arrange for care.

If you cannot reach your doctor or you don't have
one, seek care in the next hour.

You do not need to call an
ambulance unless:

You cannot travel safely either by driving
yourself or by having someone else drive you.

You are in an area
where heavy traffic or other problems may slow you down.

Call 911 Now

Based on your answers, you need
emergency care.

Call911or other emergency services now.

Heartbeat changes can include:

A faster or slower heartbeat than is normal for
you. This would include a pulse rate of more than 120 beats per minute (when
you are not exercising) or less than 50 beats per minute (unless that is normal
for you).

A heart rate that does not have a steady
pattern.

Skipped beats.

Extra beats.

Call 911 Now

Based on your answers, you need
emergency care.

Call911or other emergency services now.

After you call
911 , the operator may tell you to chew 1 adult-strength (325 mg) or 2
to 4 low-dose (81 mg) aspirin. Wait for an ambulance. Do not try to drive yourself.

Change in Heartbeat

Seek Care Today

Based on your answers, you may need care soon. The
problem probably will not get better without medical care.

Call your doctor today to discuss the symptoms
and arrange for care.

If you cannot reach your doctor or you don't
have one, seek care today.

Pain, pressure, or a
strange feeling in the back, neck, jaw, or upper belly, or in one or both
shoulders or arms.

Lightheadedness or sudden
weakness.

A fast or irregular heartbeat.

The more of these symptoms you have, the more likely it is that
you're having a heart attack. Chest pain or pressure is the most common
symptom, but some people, especially women, may not notice it as much as other
symptoms. You may not have chest pain at all but instead have shortness of breath, nausea, numbness,
tingling, or a strange feeling in your chest or other areas.

Many prescription and nonprescription drugs can cause
weakness and fatigue. A few examples are:

Antianxiety medicines.

Antidepressants.

High
blood pressure medicines.

Statin medicines for high
cholesterol.

Home Treatment

If you have generalized weakness
and fatigue along with other symptoms, evaluate those symptoms. Home treatment
for your other symptoms usually will improve your weakness and fatigue. Mild
generalized weakness and fatigue that occur with a
viral illness usually improve with the following home
treatment measures.

Get extra rest while you are ill. Let your
symptoms be your guide.

If you have a cold, you may be able to stick
to your usual routine and just get some extra sleep.

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How this information was developed to help you make better health decisions.